The present invention relates to an insulation displacement apparatus constructed such that unbared electric wire ends will be pressed into the respective wire end-receiving receptacle portions of a contact so as to establish a forced and direct electric connection between each wire end and each receptacle portion.
Each contact of a connector handled in and by any insulation displacement apparatus of this type does comprise a receptacle portion made of a flat piece of metal plate. This receptacle portion has a pair of piercing blades facing one another and defining between them a slot for receiving an unbared wire end covered with an insulation layer. With a punch pressing the wire end into this slot, its blades will make slits in the insulation layer so that the wire end is exposed in part and gripped fixedly due to a moderate force which those blades apply to said wire end.
There are certain cases wherein the insulation layer is made relatively thick to cover large-diameter electric wires, or the insulation layer itself is considerably hard and rigid. In these cases, a very strong stress will undesirably be imparted to the piercing blades, thus excessively widening the receptacle portion. In such an event, said blades would show a plastic deformation, failing to ensure a satisfactory effect of pressing and connecting the wire ends. A compartment for accommodation of each contact is defined between partitions to support the backs of said blades in the insulated housing. Therefore, those blades in such an excessively widened slot may cause these partitions to become permanently inclined, also resulting in a failure to establish an insulation displacement connection.
Some proposals have been made to provide a means for preventing such receptacle portions from being widened excessively in the described type contacts (see for example the Japanese Patent Laying-Open Gazette No. 7-272815, ibid. 10-326633 or ibid. 2000-340332).
In all the prior proposals, the means for prevention of an excessive widening of said receptacle portions comprised guide walls or guide pins disposed in and along both the sides of a punch reciprocating vertically to press the wire ends into the receptacle portions. These guide walls or pins were intended to bear sideways against a pair of partitions defining between them one receptacle portion. If however the connector comprises two or more insulation displacement type contacts, then the punch or the apparatus itself will become complicated to an undesirable degree. It may be very intricate or almost difficult to replace the pressing punch with another whenever the number of contacts changes. Further, it is an inevitable problem that relevant parts of such an apparatus become considerably expensive.
The present invention was made to resolve the drawbacks inherent in the prior art structures. Its object is to provide an insulation displacement apparatus comprising a means for protecting the insulation displacement receptacle portions of a connector from being widened, wherein this means is disposed in an insulation displacing stationary die that operates to temporarily hold therein the connector. Such a means employed in this invention has to be concise in its overall structure, easy to be replaced with another compatible one, and must be composed of simpler and inexpensive constituent parts.
In order to achieve the object, the present invention will provide an insulation displacement apparatus comprising an insulation displacing stationary die for holding in place a connector that comprises an insulated housing and a plurality of contacts each having a receptacle portion, with the contacts being individually held in compartments that are formed in the insulated housing. The apparatus further comprises an insulation displacing punch facing the die and driven to press unbared wire ends into the receptacle portions so as to establish electric connection between each wire end and each receptacle portion.
The apparatus provided herein is however characterized in that a pair of upright guards are disposed in the die so as to protect the receptacle portions from being widened during an insulation displacement operation, with the upright guards being spaced from each other a distance substantially equal to the sideways width of the insulated housing, so that end walls of the housing are propped up by the guards sideways from the outside while the insulation displacement operation is being carried out.
Particularly, the insulation displacement apparatus of the invention may be constructed such that the upright guards protrude integrally from opposite ends of a supporting plate capable of moving up and down in the die, so that upon delivery of the connector to be held in place on the die, the supporting plate will be driven upwards to cause its upright guards to prop up the end walls of the housing sideways and from the outside.
Preferably, the supporting plate is of a sideways width corresponding to multiple polarities of the punch having a plurality of pressing teeth integral therewith. If each connector has multiple polarities whose number is equal to the number of pressing teeth which the insulation displacing punch comprises, then the upright guards will be disposed at opposite ends of the supporting plate. In another case wherein each connector has a less number of polarities than the punch, one of the upright guards will be formed to be broader than the other so as to adjust a distance between them to correspond to the width of insulated housing of each connector. Further in this case, relief grooves will be engraved in the top of such a broadened upright guard so that idle teeth not pressing the wire ends are allowed to loosely fit in those relief grooves. Thus, one and the same insulation displacing punch can be used even if connectors having any different number of polarities are fed to the stationary die, by merely and simply replacing the supporting plate with another one. Now, a noticeably reduced number of constituent parts will suffice well to conduct easily and inexpensively the insulation displacement operation for electric connection.